Experimental Research On Synthesis And Chemical Properties Of Lithium With Fluorine Electrolyte Of Li-ion Batteries

The lithium-ion battery possess high operating voltage, high specific capacity and energy density which was compared to other secondary batteries. The lithium-ion battery is one of the most active research fields in modern science. Because the dihydroxybenzene and the oxalic can form an integration anion with B, they assemble new lithium salts combining with the lithium ion which should have novel structure and a good electrichemical property.The lithium-ion battery is seen as one of the best alternative batteries in the rechangeable battery market in the future. The reason is mainly on the lithium batteries which possess the high energy density, long life, high operating voltage and high specific capacity. As a reliable energy, the lithium-ion battery has been applied in small driven devices.The thesis is divided into five chapters.In the first chapter, on the basis of the large investigation of documents and analysis of summarizations, we found many lithium borates with bigπbond which is good for making up molecular designer, self-assembly more easily.In the second chapter, a series of lihium borates are synthesized which included Lithiumbis[1,2-benzenediolato(2)-O,O'-4-cyclopentene-1,2,3-trione] borate (LBDCB), Lithium[3-fluoro-1,2-benzenediolato(2-)-o,o'-4-cyclopentene-1,2,3-trione]borate (FLBDCB), Lithium[fourfluoro-1,2-benzenediolato(2-)-o,o'-4-cyclopentene-1,2,3-trione]borate(PFLBDCB). They were characterized by NMR analysis.In the third chapter, electrochemical properties of lithium borates salts with fluorine were studied. The experiment data of lithium borates had been tested by TG and cyclic voltammetry (CV) in PC, the solubility had been tested by ICP and the conductivity had been tested in different organic solvents such as PC, PC+EMC, PC+DME, PC+EC+EMC, PC+EC+DME. In the fourth chapter, using of the DFT methods, we carried on detailed theoretical researches on lithium salt LBDCB and its derivatives, and analyzed molecular structure and electronics structure of this kind of lithium salts. We also elaborated the essence of the relationships between the property (thermal stability, solubility, electric conductivity, and electrochemical stability window) and the structure.In the fifth chapter, we had succeeded in synthesizing three kinds of lithium salts. The data of experiments and tests showed that these lithium salts had higher conductivity and higher oxidized potential. Perhaps they are better electrolytes and have a great deal of uses in the field of lithium-ion batteries.In short, the structures and properties of three kinds of synthesized lithium salts had been studied in this thesis. The experimental results showed that these lithium salts might have better commercial prospects.Keywords:fluorine, croconic acid, lithium borates, electrochemical properties...